11 Difference Between Single Phase and Three Phase Power | Advantages

Do you wonder,

• Why the three-phase system is more popular and widely used than the one-phase system?
• What is the main difference between single-phase and 3 phase power systems?

In the electrical environment, most of the important and interesting topic is the alternating current (AC) electrical system. From this topic, I am describing the advantage of a three-phase system over a single-phase system.

The system of the electrical power supply is classified into two parts.

1. Single-Phase System
2. Three-Phase System

Let’s learn these terms briefly.

What is a single-phase AC system?

The arrangement of the single-phase AC power system is simple and has simple wiring construction. Completing the electrical circuit, it requires two wires (like phase and neutral).

In India, 230 V or 220 V AC supply refers to a single-phase system. This single-phase supply is used for the commercial load as well as domestic load.

What is the three-phase AC system?

The three-phase AC power system includes four wires- one neutral and three phases. These three phases are separated by an equal magnitude and120º phase difference between each other.

According to the symmetrical connection or wiring, the three-phase system is divided into two parts.

• Star connection of three-phase
• Delta connection of three-phase

As per the requirements and specifications, we can use either a star or delta connection. You can read the comparison of star connection and delta connection.

These are basic concepts of the single-phase and three-phase systems. 

After the explanation, do you have the below question in your mind?

Advantages of Three Phase Over Single Phase System

In short, Yes! The three-phase system is better than a single-phase system.

Presently, the three-phase AC system is very popular and useful for electrical power generation, distribution, and transmission systems.

A three-phase system is usually more economical than a single-phase. It is required to transmit bulk over the long transmission lines.

Now let’s see the detailed explanation-

• Why the three-phase system is better than a single-phase system? 
• What are the advantages of the three-phase system?

Difference between Single Phase and Three Phase | Advantages

Let’s compare 3 phase system with a single-phase system one by one. 

1. Circuit operation in AC system

The parallel operation of a three-phase system is easier than a single-phase system, especially in the alternator.

2. Power supply

In the single-phase system, the instantaneous AC power varies sinusoidally from zero to the peak value. This pulsating nature of power is not good for the load system.

And in the three-phase power system, constant electrical AC power is obtained due to the balanced and cumulative three-phase system.

3. Machine output 

The three-phase machine gives more output than the single-phase machine.

4. Power transmission economics

A three-phase system is more economical than a single-phase system for power transmission through the overhead line or underground cable.

The maximum amount of power is transferred through a three-phase AC supply as compared to a single-phase AC supply.

5. Working role 

Especially, domestic applications like electric motors works on the three-phase system.

For the proper working condition, three phases of the induction motor are better than the single phase of the induction motor. The three phases of the induction motor are self-starting.

6. Size of the device

If you compare the same power rating machine, the size of the three-phase machine is smaller than the single-phase machine.

7. Power efficiency

In terms of power, the three-phase system is more efficient than the single-phase system.

8. Power factor

Three-phase motors have a higher power factor as compared to single-phase motors.

9. Reliability in a fault condition

In the single-phase system, if a fault occurs in the network, then the power supply completely fails. This is because it consists of only one phase.

In a three-phase system, the network has three phases. If the fault occurs in any one of the phases, the other two phases can continuously supply the power.

From this, it is clear, that a three-phase system has good reliability than a single-phase system, in case any failure occurs.

10. Rectifier system

For the rectifier service, three-phase AC is smoother than a single-phase system. The three-phase voltage supply is easy to filter out the ripple components.

11. Maintainance

We already have seen how a three-phase system is more reliable. The three-phase supply requires less maintenance as compared to a single-phase supply.

From the above 11 reasons, the three-phase system is better than the single-phase system. Thus, a three-phase system is used in the transmission line, and a single-phase system is used in the distribution line.

If you have any specific points to discuss the difference between single phase and 3 phase, let me know in the comment.

Read some related Differences:

• Motor vs Generator
• Conductor vs Insulator
• Alternating current vs Direct current
• Series circuit vs Parallel circuit
• AC transmission vs DC transmission
• Transmission system vs Distribution system
• Core transformer vs Shell transformer
• On-grid vs Off-grid systems

Thanks for Reading!

Dipali Chaudhari

I have completed master in Electrical Power System. I work and write technical tutorials on the PLC, MATLAB programming, and Electrical on DipsLab.com portal.

Sharing my knowledge on this blog makes me happy.  And sometimes I delve in Python programming.